Apparatus for separating gas into gas components using ionization

ABSTRACT

In an apparatus for ionizing and separating a gas into gas components in an inlet gas ( 11 ), a gas flowing into a flow channel of a chamber from an inlet port is ionized, and in the flow channel the gas ionized by applying an electrical field to the gas components having an ionized state by electrodes ( 16 ) ( 17 ) is separated into a cation and anion to separate a gas molecule component contained in the gas. One of the gas component such as a clean air is removed from a first outlet ( 12 ) port and the separated gas component is removed from a second outlet ( 13 ) port. A flow of the inlet gas from the inlet port is adjusted to retain the gas in the flow channel of the chamber for a predetermined or more time so that an airflow is adjusted.

TECHNICAL FIELD

The present invention relates to an apparatus for ionizing an inlet gasand separating the gas into gas components, particularly to a gasionization/separation apparatus suitable for use as a gas separationapparatus which separate a gas into a purified gas component and othercomponents for use in a process of performing fine processing in a rangeof a nanometer to micrometer or as an cleaning apparatus for removing atrace amount of molecular components from air.

BACKGROUND ART

As a method of refining a high-purity hydrogen gas, there is a filmtransmission type refining method in which the hydrogen gas is passedthrough a film of a palladium alloy. In the film transmission typerefining method, a remarkably high separated gas component is obtained.However, in order to obtain a large amount of the refined high-puritygas, a pressure difference between the gas spaces separated by the filmneeds to be large at a high temperature. Therefore, the filmtransmission refining method requires much energy.

As a gas refining method that can be applied to many types of gases,there is an adsorption refining method of adsorbing the gas with anadsorbent. In the adsorption refining method, impurities in the gas canbe adsorbed at a normal temperature. The adsorbent adsorbing theimpurities can reactivated by treatments such as heating and reproduceadsorbability. When the gas is continuously refined, it is necessary toprepare two or more adsorption columns and alternately operate them inadsorption/desorption mode.

As a gas purifying method of a rare gas such as argon and helium or ahydrogen gas, there is a getter refining method. In the getter refiningmethod, it is necessary to react a getter material with the impuritiesin the gas at the high temperature. Therefore, the getter refiningmethod requires much energy. The getter material that has once reactedwith the impurities cannot be reproduced, and is disadvantageouslydiscarded.

On the other hand, in Jpn. Pat. Appln. KOKAI Publication No. 2001-70743,the present applicant has proposed a method of continuously purifyingthe gas with low energy. The method comprises: separating the gas intopositive and negative ions by an electrical field to purify the gas.This proposed apparatus includes a structure in which parallel plateelectrodes with gas outlets are disposed on opposite sides of a chamberto form two branching-flows. In the separation apparatus structured inthis manner, a flow branch section is the same as an ion separationregion, and the ionized impurities are separated in a minimumion-migration distance by the electrical field. Even though the ionizedimpurities, which have once moved from on one branching flow to theother branching flow are neutralized, the impurities can be taken outalong the flow. Therefore, the apparatus is superior in refining the gashaving a higher purity. However, in the structure of the parallel plateelectrodes with the outlets, a stagnant region exits in the vicinitiesof corners of the chamber. Therefore, with a high flow rate, anintroduced gas is not smoothly exhausted, and the separation efficiencyof impurities changes with the gas flow rate. Moreover, in theseparation, it is necessary to secure a retention time until theimpurities are effectively ionized. However, with the aforementionedseparator, a short-cut flow of the gas introduced in the separationchamber to the outlet is inevitable. Therefore, it is difficult tosecure the retention time even with a secured large diameter of thechamber. Moreover, a separation flow volume needs to be divided intoequal volumes. Therefore, a flow meter and valve have to be disposed atthe outlet so that the volume is adjusted into the equal volumes.However, the flowmeter cannot be disposed in an inlet of the gas flow oroutlets of the branched gases in some case. When the flowmeter cannot bedisposed, there is a problem that the flow volume cannot be adjusted.

Moreover, in separating the gas ion into two branches, a separationvoltage to be applied has an optimum value which is determined inaccordance with the flow rate of the gas, electrical mobility of theion, and generation and depletion rates of the ion. Here, the electricalmobility and generation/depletion rate of the ion vary with a pressureor temperature of the gas. Therefore, there is a problem that separationefficiency is influenced depending on a state of pressure ortemperature.

DISCLOSURE OF INVENTION

An object of the present invention is to provide an apparatus forionizing and separating a gas component in an inlet gas, which is low inenergy and high in efficiency.

According to an aspect of the present invention, there is provided anapparatus for ionizing and separating a gas into gas components in aninlet gas, comprising:

-   -   a chamber structure configured to defining a flowing channel,        which has an inlet port and first and second outlet ports;    -   an ionizer for ionizing gas components in the gas flowing into        the flow channel via the inlet port;    -   means for applying an electrical field to the ionized gas        components in the flow channel to separate the gas components        into a cation and anion, thereby separating a gas molecule        component contained in the gas;    -   means for extracting one of the gas component from the first        outlet port, and extracts the another of the gas component from        the second outlet port: and    -   control means for controlling a flow of the inlet gas from the        inlet port and retaining the gas in the flow channel for a        predetermined time period and more.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view schematically showing a two-branching-flowgas ionization/separation apparatus according to one embodiment of thepresent invention;

FIG. 2 is a cross-sectional view schematically showing an ionizer shownin FIG. 1;

FIG. 3 is a typical characteristic diagram showing one example of anexperiment result obtained by separating a trace amount of oxygen in ahigh-purity nitrogen gas in a separation apparatus shown in FIG. 1;

FIG. 4 is an explanatory view showing ionization potential and protonaffinity of nitrogen, oxygen, and toluene;

FIG. 5 is a cross-sectional view schematically showing a separationelectrode shown in FIG. 1;

FIG. 6 is a cross-sectional view schematically showing the gasionization/separation apparatus according to another embodiment of thepresent invention;

FIG. 7 is a characteristic diagram showing one example of a resultobtained by separating toluene of an organic material by the gasionization/separation apparatus shown in FIG. 6;

FIG. 8 is a characteristic diagram showing a separation efficiency inthe gas ionization/separation apparatus according to the embodiment ofthe present invention together with a related-art separation efficiencycomparative example;

FIG. 9 is a cross-sectional view showing a differential pressuredetecting method in adjusting a gas flow volume according to theembodiment of the present invention;

FIG. 10 is a characteristic diagram showing a relation between flowvolumes of opposite outlets and pressure difference according to theembodiment of the present invention;

FIG. 11 is an explanatory view showing an arrangement use example of thegas ionization/separation apparatus according to the embodiment of thepresent invention;

FIG. 12 is a cross-sectional view showing the gas ionization/separationapparatus including a pressure measurement portion which measures thepressure of the gas according to the embodiment of the presentinvention; and

FIG. 13 is a characteristic diagram showing one example of a resultobtained by solving an advective diffusion equation with respect to anmolecular component and ion to calculate a separation efficiency inionizing and electrostatically separating the molecular component in atwo-branching-flow field according to the embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

A gas ionization/separation apparatus according to an embodiment of thepresent invention will be described hereinafter in detail with referenceto the drawings.

FIG. 1 shows a gas ionization/separation apparatus of two-branching-flowtype according to an embodiment of the present invention. In the gasionization/separation apparatus, generation of an ion and separation ofthe ion by an electrical field are simultaneously performed, andelectrodes for applying the electrical field has a configuration toserve as a gas outlet port. In FIG. 1, reference numeral 11 denotes aninlet port of gas mixture, for example a mixture of air and gas, viawhich the gas mixture flows into the apparatus, 12, 13 denote gas outletports, via which the separated gas component flows out, and 14 denotes aseparation chamber in which a flow channel is defined. In the separationchamber 14, an ionizer 15 is disposed to ionize the gas components inthe flow channel. Separation electrodes 16, 17 having a structuredetachable from the chamber 14 close the chamber 14, and the outletports 12, 13 for outputting the gas components are disposed in theseparation electrodes 16, 17. The chamber 14 has a porous electrode 18and glass fiber filter 19 (flow resisting part) formed of porous memberin such a manner that the gas component flowing toward the outlet ports12, 13 pass through the member. The inlet port 11, ionizer 15,separation electrodes 16, 17, and porous electrode 18 are formed ofmetals such as SUS. For the separation chamber 14, an annularstrip-shaped portion including portions connected to the inlet port 11and ionizer 15 is formed of metals such as SUS, and the other portionsare formed of insulating materials such as quartz glass.

The separation chamber 14 is formed in a cylindrical shape, which has aninner diameter of 40 mm, and is provided with a cylindrical flowchannel, and disposed substantially horizontally in an axial direction.In left and right openings in opposite ends of the separation chamber14, the separation electrodes 16, 17 are disposed substantially inparallel with and opposite to each other so as to close the openings ofthe separation chamber 14. In a middle portion of the separationelectrode 16, the first outlet port 12 formed in a cylindrical shapewith an inner diameter of 6.2 mm is disposed. In the middle portion ofthe separation electrode 17, the second outlet port 13 formed in thecylindrical shape with an inner diameter of 6.2 mm is disposed. In themiddle portion of an outer peripheral surface of the separation chamber14, the inlet port 11 formed in the cylindrical shape having an innerdiameter of 6.2 mm is disposed to supply the gas in a peripheraldirection of the inner surface of the separation chamber 14 and generatea circular flow. Inside the respective separation electrodes 16, 17 inthe separation chamber 14, the glass fiber filters (flow resistingparts) 19, 19 are disposed to obstruct the cylindrical flow channel.Inside the respective glass fiber filters 19, 19 in the separationchamber 14, the porous electrodes 18, 18 are disposed to obstruct thecylindrical flow channel. The porous electrodes 18, 18 are disposedopposite to each other at an interval of 50 mm and substantially inparallel with each other. The ionizer 15 is disposed between the porouselectrodes 18, 18 in the separation chamber 14. The separationelectrodes 16, 17 are connected to a direct-current voltage supply 25 sothat the electrode 16 is an anode and the electrode 17 is a cathode.

In this apparatus, the gas components flow to the outlet ports 12, 13from the inlet port 11 as follows. That is, the gas introduced into theseparation chamber 14 flows along a cylindrical flow channel innersurface from a tangential (peripheral) direction. Moreover, therespective gas outlet ports 12, 13 include two types of electrodescharged in the same polarity. That is, the outlet port 12, the electrode16 and the porous electrode 18, which are located at the side of theoutlet port 12, are charged in one polarity, and the outlet port 13, theelectrode 17 and the porous electrode 18, which are located at the sideof the outlet port 13, are charged in the other polarity. In an innerspace of the hollow separation electrode 16 (17), the porous electrode18 and glass fiber filter (flow resisting part) 19 having a highpressure loss are disposed in series with each other. The gas introducedinto the flow channel in the separation chamber 14 passes through theporous electrode 18, and glass fiber filter (flow resisting part) 19 andflows out via the gas outlet port 12 (13). That is, the gas, which isintroduced into the flow channel from the side surface middle portion ofthe cylindrical chamber 14 having an inner diameter of 40 mm, arebranched towards two outlet ports 12, 13 disposed opposite to each otherand exhausted to the outside of the apparatus via the respectiveoutlets.

The gas is introduced into the separation chamber 14 from the gas inletport 11, soft X-rays are irradiated to the gas from the ionizer 15 fixedto the separation chamber 14, and the gas components are ionized in theseparation chamber 14. Certain molecular gas components, which areregarded as impurity components, are charged as the cations byion-molecule reaction. Moreover, the introduced gas is controlled sothat the gas flows in along the flow channel inner surface of thecylindrical separation chamber 14 from the tangential (peripheral)direction and the flowing gas forms the circular stream in the flowchannel. This circular flow prevents the gas flow from forming ashort-cut gas stream flowing toward the outlet ports 12, 13 from theinlet port 11. It is possible to secure a long time for which the gas isretained in the flow channel. That is, a soft X-ray irradiation timelengthens with respect to the gas, and the molecular components cansufficiently be ionized. For the respective electrodes (separationelectrodes 16, 17 and porous electrodes 18, 18) disposed in two outletports 12, 13, a direct-current voltage is applied to dispose one outletport 12 on an anode side and the other outlet port 13 on a cathode side.An electrical field is formed in the flow channel. The molecularcomponents ionized as the cations move to the outlet port 13 on thecathode side. A high-purity gas component is separated from the gas andis taken from the outlet port 12 on the anode side.

FIG. 2 is a cross-sectional view of FIG. 1. The ionizer 15 has astructure in which a soft X-ray tube 20 is located in a metal vesselsuch as SUS vessel connected to the ground. For example, the ionizer 15is fixed to a side surface portion of the separation chamber 14 with ascrew 21 from the outside. The soft X-ray tube 20 is applied with a highvoltage and is controlled by a soft X-ray control apparatus (not shown),and the soft X-ray tube 20 emits the soft X-rays into the flow channelof the separation chamber 14. It is to be noted that in FIG. 2,reference numeral 22 denotes an insulating material such as afluorocarbon resin. Moreover, the gas inlet port 11 is devised to allowthe gas to flow in along the flow channel inner surface of theseparation chamber 14 having the cylindrical shape from the tangentialdirection, so that the flow stream of the gas introduced into theseparation chamber 14 forms a circular flow 10 inside the cylindricalflow channel. By this circular flow, the gas introduced into theseparation chamber 14 flows along the inner surface of the cylindricalflow channel, and can be irradiated with a sufficient amount of softX-rays.

FIG. 3 is a characteristic diagram showing one example of an experimentresult obtained by separating a trace amount of oxygen in a high-puritynitrogen gas in a separation apparatus shown in FIG. 1. In thecharacteristic diagram, the abscissa indicates electrical fieldstrength, and the ordinate indicates the flux of separated oxygenmolecules with respect to the flux of inflow oxygen molecules via theinlet, which is separation efficiency. FIG. 3 shows a result of traceoxygen separation from nitrogen gas with inlet concentrations of 7 ppb,28 ppb, 43 ppb at an inlet flow rate of 1 L/min. The separationefficiency of oxygen increases with a lower concentration. With 7 ppb ofoxygen at electrical field strength of 2 kV/m, a maximum separationefficiency of 60% obtained. To preferentially ionize the certainmolecular component, ionization energy is requested to be smaller thanthat of a carrier gas molecule. Alternatively, proton affinity isrequested to be larger than that of the carrier gas molecule. FIG. 4shows ionization potential and proton affinity of nitrogen, oxygen, andtoluene. For nitrogen and oxygen, oxygen has a smaller ionizationpotential and is more easily charged, but a difference of protonaffinity is small as compared with organic materials such as toluene,and separation effect is low. However, it is seen that even the oxygenmolecule can be separated using the separation apparatus of FIG. 1.

FIG. 5 shows the structure of the separation electrode disposed in theoutlet port. The separation electrodes 16, 17 are constituted of hollowelectrode portions 6A, 6B formed of metals. The glass fiber filter (flowresisting part) 19 is held between the electrode portions 6A, 6B via Orings 24, and both the electrode portions are fixed with screws 23.Moreover, the separation electrodes 16, 17 are connected to thecylindrical separation chamber 14 via gastight fixing members such as Orings 44. The glass fiber filter 19 may be a micro glass fiber such as aHEPA filter, and any material may be used as long as the material has afluid resistance uniformly dispersed in the whole flow channel. Foradvantages of the filter 19 held between the electrode portions 6A, 6B,since the glass fiber filter (flow resisting part) 19 has a microstructure, contaminant such as particles are easily deposited, but thefilter can easily be changed because of the disconnectable structure ofthe electrode portions 6A, 6B. The metal porous electrode 18 is attachedto the front surface of the electrode portion 6A, that is, anupstream-side end, and the outer surface of the electrode portion 6A isconnected to the direct-current (DC) voltage supply 25. Therefore, notonly the separation electrodes 16, 17 but also the porous electrode 18can simultaneously be charged. When the separation electrodes 16, 17 arenot disposed and only the porous electrode 18 is disposed in order toconnect between the porous electrode 18 disposed inside and the DCvoltage supply from the outside of the cylindrical separation chamber14, it is necessary to make a hole in the separation chamber 14 and topass an electrical wire through the hole. However, both the porouselectrode 18 and electrode portion 6A are formed of the metals, andattached so as to be integrally molded or united, and thereby thevoltage can be applied to the porous electrode 18 by connecting the wireto the electrode portion 6A from the outside. In the porous electrode18, a fine metal mesh may be used, and any shape or material may be usedas long as the electrical fields can be formed in parallel with oneanother in the separation chamber 14 and the gas can uniformly beexhausted.

It is to be noted that the insulating material of the present apparatusis not limited to quartz glass, and materials such as a ceramic or resinmay also be used. Furthermore, a material for connecting the insulatingmaterial to the electrode or ionizer is not limited to the O ring, andsheet-shaped materials may also be used such as a metal seal of nickelplated with silver and a silicon rubber.

FIG. 6 is a cross-sectional view showing the gas ionization/separationapparatus according to another embodiment of the present invention. Asan ion source, a radioactive isotope 241 Am fixed to the cylindricalflow channel inner surface is used. In FIG. 6, the same portions asthose of FIG. 1 are denoted with the same reference numerals, and thedescription thereof is omitted. In an outer peripheral surface middleupper portion of the separation chamber 14, a cylindrical gas inlet port26 is disposed to open the chamber 14 to the outside. In a middle bottomportion inside the chamber 14, a radiation source 27 such as theradioactive isotope ²⁴¹ Am is disposed opposite to the gas inlet port 26and fixed with an epoxy resin 28. When the above-described circular flowis not used in the present embodiment, and when the flow volume islarge, there is a limitation in the amount of trace gas components,which can be ionized. However, when the glass fiber filters (flowresisting parts) 19 disposed in the inner spaces of the separationelectrodes 16, 17 of the outlet ports 12, 13 are used to rectifybranching flows, the trace gas component can steadily be ionized andseparated. Moreover, the direct-current power supplies 31, 32 bycooperating changeover switches 29, 30, can change the polarities of theelectrodes 16, 17. Thereby, a clean air or separated gas can arbitrarilybe taken out via either outlet port 12 or 13. It is to be noted thatwith the use of the radioactive isotope 241 Am and soft X-ray as the ionsources, an ion generation amount in the flow channel can further beincreased. Additionally, other ionizer such as an electrical dischargeunit can be used alone or combined as the ion source of the presentapparatus, as long as the ion can be generated.

FIG. 7 is a characteristic diagram showing one example of a resultobtained by separating toluene of the organic compound by the gasionization/separation apparatus of FIG. 6. The ordinate indicates atoluene flux with respect to an inflow toluene flux via the inlet, whichis the separation efficiency, and the abscissa indicates each separationvoltage. Toluene was separated with inlet volume concentrations of 90ppb, 190 ppb, 230 ppb. As a result, with a rise of the applied voltage,the separation efficiency of toluene rises, and the separationefficiency slightly drops with a voltage of 600 V or more. With a lowerconcentration, the separation efficiency rises. It is also seen that 78%of toluene can be separated with inlet concentration of 90 ppb.

FIG. 8 shows an experimental result obtained by comparing the separationeffect of a method using a plate electrode in the electrode of an outletmember in a gas separation apparatus using two branching-flows in theseparation chamber according to Jpn. Pat. Appln. KOKAI Publication No.2001-070743, with that of the method of the gas ionization/separation ofFIG. 6. A toluene having a concentration of 0.23 ppm in the nitrogencarrier gas nitrogen was used as a sample to be introduced into the gasinlet port. In FIG. 8, the ordinate indicates the separated toluene fluxto the inflow toluene flux via the inlet as the separation efficiency,and the abscissa indicates each separation voltage. It is seen thattoluene is hardly separated in any voltage with a flow rate of 2 L/minin the method using the related-art plate electrode. This is because astagnant region exist in the chamber corner, influence of disturbance ofthe flow becomes remarkable with a large flow volume, and toluene cannoteffectively be separated. However, when the separation electrodes 16, 17and porous electrodes 18, 18 are used as the electrodes in the outletports 12, 13 of FIG. 6, and the glass fiber filters (flow resistingparts) 19 are further disposed, the separation of toluene occurs withthe separation voltage. At 600 V, 0.23 ppm of toluene can be separatedby 24% at maximum. From this, it is seen that the separation efficiencyrises in any separation voltage with the improved structure of theseparation electrodes 16, 17 shown in FIG. 5.

It is to be noted that in the present embodiment, the inside of thewhole separation chamber 14 is assumed to effectively function as thegas flow channel, a flow channel volume is 62.8 mL (flow channel innerdiameter=40 mm, flow channel length=50 mm), an inlet gas flow rate is 2L/min, and an average retention time of the flow gas in the presentapparatus is 1.8 sec. When the flow stream of the gas introduced intothe flow channel is controlled so as to form the circular flow in theflow channel under this condition, the average retention time of theinlet gas further lengthens, and a large separation efficiency can beobtained.

FIG. 9 shows the gas ionization/separation apparatus in which a gaspressure difference between both the outlet ports is detected by adifferential pressure gauge to adjust an outlet flow volume. In FIG. 9,the same portions as those of FIG. 6 are denoted with the same referencenumerals, and the description thereof is omitted. With the use of thegas flowing out via the anode, in order to easily adjust the outlet flowvolume of the present apparatus, holes (diameter of 0.6 mm) are made inthe electrodes 16, 17 of the opposite outlet ports 12, 13 until holes 33reach gas pipes (inner diameter of 6 mm) 34. This method furthercomprises: measuring the pressure difference between the opposite outletgases with a differential pressure gauge 35; and opening/closing a flowvolume adjustment valve 36 disposed in the outlet port 13 so as toobtain a differential pressure of 0. In this method, without measuringthe flow volumes of the inlet port 11 and outlet ports 12, 13 with aflow volume meter, the flow volume of the gas ionization/ separationapparatus can be controlled to obtain a predetermined flow volume. Thiscontributes reduction of an apparatus cost and stabilization of control.It is to be noted that the holes 33 for the differential pressuremeasurement may be disposed on either upstream or downstream side of theglass fiber filter (flow resisting part) 19, and need to be opened inleft and right positions. The values of the flow volume and pressureneed to be calibrated beforehand for use.

FIG. 10 shows a result obtained by making the holes 33 each having adiameter of 0.6 mm vertically in the gas pipes (inner diameter of 6 mm)34 of opposite outlets and checking a relation between a statisticpressure difference and flow volume ratio in the gas pipes 34 of therespective outlets. The abscissa indicates a ratio of a flow volumeCout1 of one outlet 12 with respect to a flow volume Cin of an inlet 26,and the ordinate indicates a result of measurement of a static pressuredifference ΔP. It is seen from FIG. 10 that the difference between theoutlet flow volumes can be obtained with the static difference ΔP. Thisis the result of the measurement of the static pressure difference, buta dynamic pressure difference or whole pressure difference may also bemeasured.

FIG. 11 shows a example in which a large number of gasionization/separation apparatuses according to the embodiment of thepresent invention are used in one parallel stage and one series stage.When the apparatuses are arranged in parallel with each other, it ispossible to treat the inlet gas with a large flow volume which cannot becompensated with one apparatus. Moreover, when the present apparatusesare disposed in series with each other, a high-efficiency separated gascan be refined. This cannot be achieved with one apparatus.

FIG. 12 shows the gas ionization/separation apparatus including apressure measurement portion which measures the pressure of the gas andtemperature measurement portion which measures the temperature of thegas according to the embodiment of the present invention. In FIG. 12,the same portions as those of FIG. 6 are denoted with the same referencenumerals, and the description thereof is omitted. The holes (diameter of0.6 mm) are made in the separation electrodes 16, 17 of the outlet ports12, 13 until the holes 33 reach the gas pipes (inner diameter of 6 mm)34. The pressure of the fluid is measured with a pressure gauge 37, andthe temperature is measured with a temperature meter 38. The outlet port13 includes a flow volume adjustment valve 39. In a circuit whichapplies the separation voltage, a variable resistor 41 is attached asvoltage adjustment means in series with a direct-current voltage supply40. When the pressure of the fluid in the apparatus rises or thetemperature of the flowing gas drops because of pressure resistance of apiping system connected to the apparatus, the variable resistor 41 isadjusted, a larger separation voltage is applied, and thereby theseparation efficiency can be prevented from dropping. It is to be notedthat the hole 33 to which the pressure gauge 37 or temperature meter 38is to be attached may be disposed in any position of the apparatus flowchannel. The holes may also be made in the flow channel outside theapparatus, as long as the pressure or temperature meter in the apparatusis measured/known. Furthermore, the same hole may be used to dispose thepressure gauge and temperature meters in the same position.

FIG. 13 is a characteristic diagram showing one example of a resultobtained by solving an a convective diffusion equation with respect tothe molecular component and ion to calculate the separation efficiencyin ionizing and electrical migration of trace gas component in atwo-branching-flow field. The generation of the toluene ion is definedas a first order reaction in proportion to the concentration of toluenemolecules and the depletion of the toluene ion is defined as the firstorder reaction in proportion to the concentration of toluene ions toperform the calculation. Here, Z denotes an electrical mobility of theion, u denotes a flow velocity of the gas, α denotes a depletion rateconstant of the ion, and β denotes a generation rate constant of theion. It is seen that an optimum voltage for separating the trace gascomponent most changes with a change of the electrical mobility of theion. Parameters such as electrical mobility and rate constant changewith the temperature, pressure, or type of the gas. Therefore, in thiscase, it is seen that an optimum separation voltage is obtained for thepressure or temperature of the gas measured using the pressure gauge 37or temperature meter 38, the applied voltage is adjusted by voltageadjustment means, and thereby optimum separation can constantly beperformed.

It is to be noted that instead of the adjustment of the voltage, thetemperature or pressure may also be controlled by temperature orpressure adjustment means disposed, for example, in the inlet 26, or thevoltage/temperature/pressure may also be adjusted.

The present invention has been described above based on the embodiments,but is not limited to the embodiments, and can variously be changedwithout departing from the scope. For example, the flow channel in theseparation chamber is not limited to the cylindrical channel. When theflow channel is molded in a tubular shape so as to form the circularflow by the inlet gas inside the channel, a sufficient gas retentiontime can be secured, and it is possible to effectively generate the ionin the flow channel. Moreover, means for retaining the gas in the flowchannel for a predetermined or more time is not limited to a method offorming the circular flow. A method of disposing controlling means suchas a baffle plate and guide member in the flow channel and allowing theinlet gas to meander in the flow channel may also be used. At this time,in the structure of the inlet port, the gas does not necessarily have tobe introduced along the flow channel inner surface from the tangentialdirection. Moreover, the direct-current voltage supply for forming theelectrical field may be of any type such as a type for applying apositive and/or negative voltage, as long as a predetermined voltage canbe applied. Furthermore, the voltage, temperature, or pressure maymanually or automatically be controlled. Some of the gas components arecharged in the negative ions. When there are a large number of suchcomponents, the components may also be separated in the anode.

As described above, in the method of branching the gas introduced fromthe middle of the separation chamber into two in opposite directions,forming each outlet by the porous separation electrode, and holding thechamber between the electrodes, the stagnation portion of the flow iseliminated. With a high-pressure loss member (HEPA filter) disposedbehind the porous member (porous electrode), the gas which has enteredthe separation chamber is rectified so as to flow along the wholechamber. Furthermore, when the circular flow is formed in the chamber inorder to secure the retention time of the gas introduced into thechamber, the retention time for ionizing and separating the ion can besecured. Therefore, there can be provided the gas ionization/separationapparatus, which is high in efficiency and low in energy.

Moreover, when the differential pressure is measured from the staticpressure of the gas in each outlet, without measuring the outlet flowvolume, the differential pressure can be adjusted, and the flow volumecan also be adjusted. When the polarity of the electrode is changed, theseparated gas can be taken out via either outlet. Furthermore, with theuse of a large number of separation apparatuses of the presentinvention, a large flow volume which cannot be compensated with oneapparatus can be handled. Even the high efficiency separated gas, whichcannot be achieved with one apparatus, can be separated.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventionconcept as defined by the appended claims and their equivalents.

1. An apparatus for ionizing and separating a gas into gas components inan inlet gas, comprising: a chamber structure configured to define aflowing channel, which has an inlet port and first and second outletports; an ionizer for ionizing gas components in the gas flowing intothe flow channel via the inlet port; means for applying an electricalfield to the ionized gas components in the flow channel to separate thegas components into a cation and anion, thereby separating gas moleculecomponents contained in the gas; means for extracting one of the gascomponents from the first outlet port, and extracting another of the gascomponents from the second outlet port; and control means forcontrolling a flow of the inlet gas from the inlet port and retainingthe gas in the flow channel for a predetermined time period and more. 2.The apparatus according to claim 1, wherein the controlling meansincludes a flow resisting part, which are disposed in each of the firstand second outlet ports.
 3. The apparatus according to claim 1, whereinthe controlling means includes a flow resisting part to allow the gascomponent to flow out of the flow channel, and applying means includesfirst and second electrodes disposed in the first and second outletports, respectively, and disposed opposite to each other to separate thegas components into a cation and anion so that gas molecule componentcontained in the gas are separated.
 4. The gas ionization/separationapparatus according to claim 3, wherein the first and second outletports are provided with first and second porous electrode formed of aporous member as a part of the first and second electrodes,respectively, and the one gas component and the other gas component arepassed through the first and second porous electrodes and the flowresisting part, and are extracted from the first and second outletports, respectively.
 5. The apparatus according to claim 2, wherein theresisting part are detachably provide in front of the outlet ports,respectively.
 6. The apparatus according to claim 1, wherein thecontrolling means allows the gas component to flow in along an innerperipheral surface of the flow channel from the inlet port, and forms acircular flow in the flow channel, so that the inlet gas flow isretained in the flow channel.
 7. The apparatus according to claim 1,wherein the flow channel is molded in a cylindrical shape, the inletport is disposed in a side surface portion of the cylindrical flowchannel, and the first and second outlet ports are disposed opposite toeach other in opposite ends of the cylindrical flow channel.
 8. Theapparatus according to according to claim 1, wherein the ionizerincludes a plurality of ion sources for ionizing the gas component. 9.The apparatus according to claim 1, wherein the controlling meansincludes a pressure measurement portion configured to measures apressure of an outflow gas, and a flow volume adjuster configured toadjust the flow volume of the gases extracted from the respective firstand second outlet ports based on a pressure difference between the gascomponents measured in the first and second outlet ports.
 10. Theapparatus according to claim 1, further comprising: means for changingpolarity of the electrode which applies the electrical field and meansfor changing electrical field strength of the electrode.
 11. Theapparatus according to claim 1, further comprising: means for changingpolarity of the electrode which applies the electrical field.
 12. Theapparatus according to claim 1, further comprising means for changingelectrical field strength of the electrode.
 13. apparatus according toclaim 1, further comprising: temperature measurement means for measuringa temperature of the gas in the flow channel so that an optimumseparation voltage is applied in accordance with the measured gas. 14.The apparatus according to claim 1, further comprising: pressuremeasurement means for measuring a pressure of the gas as a gas state inthe flow channel so that an optimum separation voltage is applied inaccordance with the measured gas component.
 15. The apparatus accordingto claim 1, further comprising: temperature measurement means formeasuring the temperature of the gas in the flow channel so that the gasstate is adjusted to have an optimum temperature in accordance with theapplied separation voltage.
 16. The apparatus according to claim 1,further comprising: pressure measurement means for measuring thepressure of the gas as a gas state so that the gas state is adjusted tohave an optimum pressure in accordance with the applied separationvoltage.